Industrial, manufacturing, petrochemical and other “automation industries” implementing complex processes and systems have been migrating from proprietary, centralized architectures to open, decentralized architectures to facilitate automation of such processes and systems. Decentralized architectures commonly implement fieldbus control systems and networks wherein control is distributed amongst the various devices within the network and/or system. Examples of open, interoperable and decentralized fieldbus architectures include the FOUNDATION™ fieldbus from the Fieldbus Foundation (Austin, Tex.), PROFIBUS from PROFIBUS International (Karlsruhe, Germany); LonWorks from Echelon Corporation (San Jose, Calif.), industrial Ethernet and others (hereafter, collectively “fieldbus Architectures”).
The demand for open and interoperable, distributed control fieldbus systems is often driven by equipment suppliers and users. Suppliers commonly prefer fieldbus Architectures because it allows them to sell their products and/or services to more users, instead of only to users operating a specific proprietary system. Users desire to utilize fieldbus Architectures, for example, because it often enables them to select the fieldbus devices and/or services from multiple suppliers instead of only devices specifically designed for a proprietary system.
Many sectors of the automation industry also have a need for special “safety” systems to ensure the safety of plant personnel and to prevent damage to equipment due to unexpected events. These special “safety” systems are collectively called “Safety Instrumented Systems” (SIS). Users and suppliers often require SIS systems to comply with international safety standards such as International Electotechnical Committee (IEC) 61508 (functional safety of electrical/electronic/programmable electronic safety-related systems), and IEC 61511 (functional safety: safety instrumented systems for the process industry sector). Currently available SIS control solutions are commonly proprietary and are not compatible with fieldbus Architectures.
Thus, users and suppliers of SIS devices and systems have a need for an open, interoperable SIS fieldbus Architecture (hereafter, an “SIS fieldbus”) that enable users to support and/or provide SIS control using existing fieldbus Architectures. Desirably, an SIS fieldbus is directly compatible with existing fieldbus Architectures and do not require modification to existing communication protocols, function blocks and/or other network aspects.